Electric heater.



coating UNIKTED STATES PATENT @lfilllllGE GEORG EGLY, 0F TREPTOW, GERMANY, ASSIG-NQR T0 GEBRUEDER SIEMENS & C0., 0F BERLIN, GERMANY, A CORPORA'EIUN 01E GERMANY- ELECTRIC HEATER.

mosses. No Drawing.

To (115 whom it may concern:

Be it known that I, Guess EeLY, a c1t1- zen of the German Empire, and residing at 'lreptow near Berlin, Germany, have invented certain new and useful Improvements in Electric Heaters, of which thefollowing isa specification.

My invention. relates to electric heaters composed of non-metallic reslstance materials. Heaters consisting of non-metallic resistance materials, 6. g. silit, are preferably made more conductive, at the places to which the current is supplied, and at the places adjacent thereto, by means of a metallic or by impregnation with metals. Coatings of silver are principally employed for thepurpose. The heaters are usually porous and the metal penetrates more or less deeply into them. I The coatings not only cause better contact but, owing to their greater conductivity, lessen the glow in the vicinity of the contact-pieces and protect the latter from being burnt. It has however been found that such metallic coatings melt when the temperature ishigh, and that they gradually recede toward the contact-pieces, toward which the glow therefore continually advances.

A primary object of my invention is-to obviate this defect. To this end, 1 coat that part of the heater which is coated or impregnated with a metal with a glaze such as boracic acid, borates or the like. The effect of this glaze is surprising; the metal entirely ceases to recede, the glow no longer advances along the heater, and the heater remains practically unchanged although its temperature may be considerably above that of th melting point of the metallic coating. It is difficult to assign a reason for the action of the glaze. It is possible Specification of Letters IPatent.

Application filed April 8, 1913. Serial Ito. 759,803.

lPatented'July ML, 1914..

that changes in the conduction and radiation of the heat play some part. Perhaps the glaze in some way directly either prevents the molten metal fromshrinking together, or prevents it from exuding from the pores of the heater. The heaters are as a rule porous, and when treated with the metal, the 'latter penetrates more or less deeply into the interiortflt' the same. When .the glaze is lacking, the metal seems to ex- 1. An electric heater composed of a nonmetallic, highly refractory resistance material provided in the vicinity of the places at which current is supplied with a metallic coating and with a glaze on the metallic coating, for the purpose specified.

2. An electric heater composed of a nonmetallic, highly refractory resistance mate rial providedin the vicinity of the places at which current is supplied with a metallic coating glazed with .a compound of boron,

for the purpose specified.

In testimony whereof, have signed my name to this specification in the presence of two witnesses.

Geese EGLY.

Witnesses:

. HENRY HASPER,

VVOLDEMAR HAUJPT. 

